NCIS investigates the death of a retired Navy officer who's son was convicted of a murder 16 years before. A flawed forensic test from that time can prove whether the son was the real murderer or innocent of the crime. When the body of a retired navy officer
is found, the team goes to investigate. When they learn who he is, Ducky says he needs to be step down. He doesn't say why. Gibbs presses and Ducky admits he joined a group of amateur sleuths who go over unsolved cases. And the Navy Officer approached them
to investigate the murder his son was convicted of 16 years ago. Gibbs goes over the murder and it was suspected that another man may have committed the murder but evidence led to the man's son. Gibbs goes to see the suspect who admits the man's father was
hounding him to admit to the murder. But he says he didn't do it and that someone's already questioned him. They learn it's one of the sleuths so Gibbs goes to see them but they are obstinate. So Gibbs brings them in and has the team question them. They later
tell them something which they then tell Gibbs. That the test which incriminated the officer's son was flawed. They implore Gibbs to reopen the murder but Gibbs refuses to do that, till he is told who performed the original test, Abby.